Low-voltage protective circuit controller



Jan. 22 1924.

G. E. LAUE LOW VOLTAGE PROTECTIVE CIRCUIT CONTROLLER Filed Jan. 26. 1921 R1 MM IMAM/LON Gum/vb E. Laue B l I l Patented Jan. 22, 1924.

UNITED STATES PATENT OFFICE.

GILBERT E. LAUE, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO THE CUTLER- HAMMER MFG. CO., OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

LOW-VOLTAGE PROTECTIVE CIRCUIT CONTROLLER.

Application filed January 26, 1921. Serial 1%. 440,060.

To aZZ whom it may concern:

Be it known that I, GILBERT E. LAUE a citizen oi? the United States, residin at Milwaukee, in the county of Milwau ee and 5 State of Wisconsin, have invented new and useful Improvements in Low-Voltage Protective Circuit Controllers, of which the following is a full, clear, concise, and exact description, reference being had to the accom panying drawing, forming a part of this specification.

This invention relates to low voltage protective circuit controllers.

Heretofore it has been proposed to provide a controller of the aforesaid character comprising an electro-responsive main switch, a manual switch to control the same under normal voltage conditions and a low voltage relay also controlling said main switch, said relay having circuit connections controlled by special contacts of the manual switch to necessitate positioning of the latter switch to interrupt the energizing circuit oi the main switch prior to resetting of the relay following low voltage operation thereof. In other words, the manual switch has been provided with special contacts controlling the relay to insure against automatic resetting thereof following low voltage operation of the same and hence insuring against automatic response of the main switch to reclose the controlled circuit upon restoration of normal voltage conditions which protection is often essential especially in motor control.

The present invention has amon its objects to provide a controller affording the same protection but obviating the necessity of providing the control switch with special contacts for the purpose stated.

Another object is to provide a controller wherein the circuit connections required to insure against automatic resetting of the relay are placed under control by Said relay whereby the proposed form of controller may be readily obtained by slight modification of various forms of controllers now in use but lacking the aforestated protective feature.

Another object is to provide a controller of the aforestated character which may be employed for either direct or alternating current circuits.

Another object is to provide a controller having the characteristics aforedescribed and including one or more additional switches to control the main switch through the medium of the low voltage relay but subject to certain restrictions hereinafter set forth.

Various other objects and advantages of the invention will hereinafter appear.

The accompanying drawing diagrammatically illustrates one embodiment of the invention and the same will now be described, it being understood that the invention may be embodied in various other forms falling within the scope of the appended claims.

In the drawing Fig. 1 is a simplified diagrammatic view of a circuit controller particularly designed for;i control of a direct current motor circuit; an

Fig. 2 is an across-the-line diagram of the controller shown in Fig. 1.

Referring to Fig. 1, the same shows a di rect current compound motor M which it may be assumed is employed in elevator service, said motor to be supplied with current from supply lines L and L and to be accelerated through the medium of a suitably controlled resistance R.

The controller comprises an electro-responsive main switch 1 controlling the continuity of the motor circuit, a manual switch 2 controlling said main switch, a low voltage relay 3 also controlling said main switch and a number of series connected switches 4: to control the main switch through the medium of the relay 3. While for simplicity of illustration no reversing means has been shown, it is of course to be understood that either manual or power operated reversing means may be employed.

The switch 2 may be incorporated in any desired control instrumentaliiy such as the car switch of an elevator controller or it may be independent of all other control instrumentalities while the switches 4 may comprise the usual door switches of an elevator control system although it is to be understood that said switches may be provided in any desired number for operation by any desired instrumentalities.

The relay 3 comprises a contact arm tending to stand in a position to engage a fixed contact and attractable by an electromagnet 3 to disengage contact .5 and to engage a fixed contact 6. The winding 3 as best illustrated in Fig. 2, is connected across the line L and L through a resistance R and switches 4, said resistance being interposed between said winding and line l5 and switches 4 being connected in series between said winding and line L. Also the winding 3 has a connection extending from a point between said winding and the resistance R to and through the lower contacts of relay 3 by conductor 7 (Fig. 2) through switch 2 to line L.

The resistance R is of such value as to permit, under normal conditions, a sufficient flow of current through the winding 3 to effect response of relay 3 and thus assuming the switch 2 to be open and all of the switches 4 to be closed, and further assuming normal voltage conditions, the circuit connections described provide for energization of winding 8 to operate relay 3.

Response of relay 3 interrupts the connection between its winding 3 and switch 2 and engages its upper contacts to complete a connection between switch 2 and the operating winding 1" of main switch 1. Thus, upon closure of switch 2 the "energizing circuit oi main switch 1 is completed to effect response of said switch, said circuit as best shown in Fig. 2 extending across lines L and L through switch 2 and relay 3 in series.

Thus assuming energization of the relay and main switch as set forth, it will be observed that an abnormal drop in voltage will eiiiect release of relay 3. The relay wlll then assume the position illustrated thereby interrupting the connection between the main switch winding 1 and the switch 2 at the same time reesta'blishing the connection between switch 2 and the relay winding 3". Accordingly, the relay establishes a shunt t'or its winding 3 through the switch 2 which prevents resetting of said relay until the switch 2 is opened to interrupt said shunt and the circuit of main switch winding 1. When the switch 2 is opened and normal voltage conditions are restored, the relay will at once respond thus enabling reenergization of the main switch by reclosure of switch 2.

Again assuming energization of relay 3 and main switch 1, opening of any one of the switches 4t will ole-energize the relay with the result of de-energizing the main switch and establishing the aforedescribed shunt for the relay winding 3 through switch 2. Under such conditions it will be apparent that resetting of the relay will be dependent upon reclosure of the open switch t and opening of switch 2. Thus subsequent energization of the main switch is rendered dependent upon operation of the switches 4: and 2 in a definite sequence, i. e., reclosure Leaner? of switch 2 after reclosure of the switch t. lt will accordingly be observed that the controller illustrated is particularly advantageous for elevator se vice, it being desired to insure against restarting by closure of the door switches or any switches other than the car switch in which the switch :2 is assumed to be embodied.

Vi hat claim as new and desire to secure by Letters la tent is:

1. ln a low voltage protective circuit controller in combination, an electro-responsive switch, a control switch therefor in circuit with the winding thereof, and a low voltage relay also controlling said electro-responsive switclnsaid relay having sell controlled circuit connections rendering its setting operation dependent upon predetermined positioning oi said control switch.

2. in a low voltage protective circuit controller, in combination, an electro-responsive switch, a control switch therefor, and a low voltage relay also controlling said electroresponsive switch, said relay having contacts engageable upon low voltage operation to complete a shunt for its operating winding through said control switch when in a position to energize said electro-responsive switch.

3. In a low voltage protective circuit con troller, in combination, an electro-responsive switch, a manual control switch therefor and a low voltage relay also controlling said electro-responsive switch, said relay} having line connections for its operating winding including a resistance and having contacts to complete a circuit through said manual switch shunting said relay winding to necessitate predetermined positioning of said manual switch "for resetting of said relay following low voltage operation of the latter.

4. In a low voltage protective circuit controller in combination, an electro-responsive switch, a manual switch having contacts to make and break the energizing circuit of said electro-responsive switch and a low voltage relay also controlling said electroresponsive switch, said relay having circuit connections and contacts subjecting the same to control by said contacts of said manual switch whereby resetting of said relay r'ollowing low voltage operation thereof is rendered depen dent upon positioning of said manual switch to interrupt the energizing circuit oi :--;aid electro-responsive switch.

5. in a low voltage protective circuit controller in combination, an electro-responsive main switch, a control switch therefor connected in the energizing circuit thereof, a low voltage relay controlling said main switch, a switch controlling said main switch through the medium of said relay and circuit connections for said relay necessitating certain operations of said control switches in a definite sequence to eflt'ect resetting of said relay following de-energization thereof by the last-mentioned control switch.

6. In a low voltage protective circuit controller in combination, an electro-responsive mainswitch, a control switch therefor connected in the energizing circuit thereof, a low voltage relay also controlling said main switch, said relay having line connections for its winding including a resistance and having contacts to complete circuit between said resistance and one line which circuit includes said control switch and shunts said relay winding, and a switch for controllin said main switch through medium of said relay, the latter switch being in series with said relay winding and included between said winding and the last-mentioned line.

In witness whereof, I have hereunto subscribed my name.

GILBERT E. LAUE. 

